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CO2 Through the Ages

In my book, Nothing to Fear, I use the 2,000 year period between today and the time of Christ to demonstrate that there is no clear evidence that atmospheric CO2 levels have had an effect on temperatures. For example, the medieval warm period had temperatures as high as today’s, while CO2 levels were unchanged.

In the book, I use an IPCC chart showing that, prior to around 1850, atmospheric CO2 levels were constant at around 280 ppm going back for 2,000 years. I used the IPCC chart since few people would likely criticize the data.

GHG Graph from IPCC AR4

In my talks, I go back 4,000 years to make the same point.

4,000 year history of temperatures and CO2

During this 4,000 year period, there have been four warm periods, including today’s. In the previous warm periods, Medieval, Roman and Minoan, temperatures have been as high, or higher, than they are today, while atmospheric CO2 has remained essentially constant at around 280 ppm.

This again supports the contention that CO2 is having little effect on temperatures rise.

It’s possible to go back hundreds of thousands of years and still see that CO2 hasn’t seemed to affect temperatures. I didn’t propose going back that far in my book since there were so many other forces at work about which much is still unknown.

During the Carboniferous period, for example, the formation of skeletal life drew CO2 from the atmosphere and locked it permanently in the Lithosphere as Limestone.

However, as the following chart shows, atmospheric CO2 has been very much higher than today, while CO2 levels over the past three million years have been among the lowest levels during the Earth’s history. Meanwhile temperatures have varied widely, with little correlation to atmospheric levels of CO2.

While these records comparing atmospheric CO2 levels with variations in temperatures provide substantial proof that CO2 has not been the primary cause of temperature change, they do not infer that CO2 hasn’t had some effect on temperatures.

They also don’t infer that mankind hasn’t affected the environment.

They do, however, demonstrate that the CO2 hypothesis, claiming that atmospheric CO2 is causing global warming and climate change, is unsubstantiated, and that history has shown there is little correlation between CO2 and temperatures.

Geologic Time Scale CO2 and Temperatures

There are other hypotheses for the cause of global warming with greater scientific support than the CO2 hypothesis.

For example, there is Dr. Svensmark’s hypothesis, where cosmic rays create low-level clouds that shade the Earth and reflect sunlight back into space. This is explained more fully in Nothing to Fear.